Damper housing structure body and damper housing structure body fabrication method

ABSTRACT

In a damper housing structure body, an upper edge of a damper housing and a damper base are bonded by spot welding. The damper housing has a U-shape with an opening on a vehicle outer side in plan view, and includes a planar part in a corner between a front wall and an inner wall. The planer part includes plural welding spots arranged in the front-rear direction of the vehicle. Adjacent weld spots have mutually overlapping welding margins or an interval between two adjoining welding points is shorter than an outer diameter of the welding margins. One of the welding spots is welded while a current is applied to another welding spot that has been already welded. A current value for welding the one of the welding spots is higher than another current value for another one of the welding spots that has been already welded.

TECHNICAL FIELD

The present invention relates to a damper housing structure body and adamper housing structure body fabrication method in a vehicle.

BACKGROUND ART

Suspension devices (suspensions) for a vehicle installed on both sidesin an engine room are supported through damper bases which are supportedby damper housings which are located at top surfaces of the housings(see Patent Document 1). The damper base and the damper housing aresubject to loads during travelling. Particularly, during traveling on arough road, an excessive load is inputted thereto. Accordingly, aconsiderable bonding strength is required.

The damper base is joined with the upper edge of the damper housing byspot welding. It is known that the load during travelling isconcentrated at a front corner of the upper edge of the damper housinghaving a U-shape in a plan view. This part cannot be welded for joining,so that it is difficult to secure the bonding strength by the spotwelding. Accordingly, a necessary strength is secured by reinforcementwith another member, an increase in a plate thickness, a modification ofa shape of the damper base, etc (see Patent documents 2, 3, and 4).

PRIOR ART Patent Document

-   PATENT DOCUMENT 1; JP 2006-56489 A-   PATENT DOCUMENT 2; JP 2009-292226 A-   PATENT DOCUMENT 3; JP 2004-276789 A-   PATENT DOCUMENT 4; JP 2007-284008 A

SUMMARY OF INVENTION Problem to be Solved by Invention

However, in the technologies described in Patent Documents 2, 3, and 4,there are problems in increase in weight resulting from reinforcementwith another member, increase in thickness of plate members, or increasein weight resulting from improvement of a shape of the damper base, andincrease in a man-hour resulting from reinforcement with another member.

The present invention has been developed in consideration of thecircumferences described above and aims to provide a damper housingstructure body and a damper housing structure body fabrication method inwhich a damper housing and a damper base are secured in a bondingstrength with avoidance of increase in the weight and man-hour.

Problem to be Solved by Invention

To solve the above-described problems, the present invention ischaracterized in that;

-   -   a damper housing configured to house a damper of a suspension        device of a vehicle; and    -   a damper base, disposed at a top of the damper housing, fixed to        the damper, wherein    -   an upper edge of the damper housing and the damper base are        bonded by spot welding, wherein    -   the damper housing having a U-shape in a plan view thereof with        an opening toward a vehicle outer side and including a planar        part at a corner part between a front wall and an inner wall        thereof, wherein    -   the planar part includes a plurality of welding spots arranged        in a vehicle front-rear direction, and wherein    -   the welding spots adjoining each other have welding margins        which are overlapped each other.

To solve the above-described problems, the present invention ischaracterized in that

-   -   a damper housing configured to house a damper of a suspension        device of a vehicle; and    -   a damper base, disposed at a top of the damper housing, fixed to        the damper, wherein    -   an upper edge of the damper housing and the damper base are        welded by spot welding, wherein    -   the damper housing having a U-shape in a plan view thereof with        an opening toward a vehicle outer side and including a planar        part at a corner part between a front wall and an inner wall,        wherein the planar part includes a plurality of welding spots        arranged in a vehicle front-rear direction, and wherein    -   an interval between two of the welding spots adjoining each        other is shorter than an outer diameter of the welding margin.

According to the above-described structure, the spot welding is carriedout at a plurality of spots at a narrow interval at a planar part at acorner part between the inner wall and the front wall of the damperhousing, which was conventionally difficult. Accordingly, the strengthcapable of bearing the travelling load at the damper housing can beprovided. Further, it becomes possible to reduce a plate thickness ofthe damper housing because of the increased strength, which provides aweight saving and a cost reduction of the vehicle body. Further, aproperly distributing a plurality of welding spots can decrease thenumber of total impact spots, which provides reductions in cost and inman-hours. Further, a ridge line between the front wall and the planarpart and a ridge line between the inner wall and the planar partappropriately disperse the travelling load applied to the damper housingfrom a downward direction, so that a concentration of the load can beavoided.

Another configuration may be provided in which one of the welding spotsis welded while a current is also applied to other welding spots havingbeen already welded.

According to this configuration, a plurality of welding spots are notformed instantaneously but sequentially formed. When one welding spot isformed by welding, bonding is provided while currents are applied toother welding spots which have been already formed. Accordingly, aplurality of welding spots can be formed at a narrow part, which wasconventionally difficult, so that a strength enough to stand thetravelling load in the damper housing can be provided. Further, increasein the strength can reduce a thickness of the damper housing 2, so thatweight saving and cost reduction for the vehicle body can be provided.Further, appropriate allocation of a plurality of welding spots canreduce the total number of spots, which provides reduction in cost andin the man-hours.

It is desirable that a current value for the one of the welding spotsfor welding is higher than a current value for another one of thewelding spots that has been already welded.

According to this structure, when the one of the welding spots isformed, the current value for the one of the welding spots is higherthan the current value for the welded spot that has been already formed.Accordingly, a plurality of welding spots can be provided at the narrowspace, which has been difficult. Thus, the strength enough to stand thetravelling load can be secured. Further, the increased strength makes itpossible to reduce the plate thickness in the damper housing, whichprovides weight saving and cost reduction of the vehicle body. Further,appropriate allocation of the welding spots results in the total numberof impact spots, which provides advantageous effects in the costreduction and reduction in man-hours.

The width of the planar part may be substantially the same as a sum ofouter diameters of a plurality of the welding spots.

According to the structure, because the width of the planar part issubstantially the same as the sum of outer diameters of a plurality ofthe welding spots, the stiffness enough to stand the travelling load inthe damper housing can be provided. Further, the increased strengthmakes it possible to reduce the plate thickness in the damper housing,which provides weight saving and cost reduction of the vehicle body.Further, appropriate allocation of the welding spots results in decreasein the total number of impact spots, which provides advantageous effectsin the cost reduction and reduction in man-hours.

To solve the above-described problems, the present invention provides adamper housing structure body fabrication method of producing a damperhousing structure body including: a damper housing configured to house adamper of a suspension device of a vehicle; and a damper base, disposedat a top of the damper housing, fixed to the damper, the methodcomprises:

-   -   the damper housing has a U-shape in a plan view thereof with an        opening toward a vehicle outer side and include a planar part at        a corner part between a front wall and an inner wall; and    -   performing spot welding at a plurality of welding points        arranged in a front-rear direction of a vehicle, wherein    -   the welding points adjoining each other having welding margins        which are overlapped each other or an interval between two        adjoining welding points is shorter than an outer diameter of        the welding margins.

Accordingly, the one of the welding spots can be formed by applying acurrent also to the welding spot that has been already formed.

It is desirable that the one of the welding spots is welded at a currentwhich is higher than another current value for another one of thewelding spots that has been already welded.

Advantageous Effect of Invention

According to the present invention, a joint strength between the damperhousing and a damper base can be secured while increase in weight andthe number of man-hours are avoided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a vehicle including a damperhousing structure body according to embodiments of the presentinvention.

FIG. 2 is an enlarged perspective view showing a damper housingstructure body.

FIG. 3 is an exploded perspective view showing a damper housing and adamper base.

FIGS. 4A to 4E are drawings illustrating bonding between the damperhousing and the damper base in which FIG. 4A is a perspective viewshowing the damper housing and the damper base, FIG. 4B is an enlargedview showing a part A1 in FIG. 4A, FIG. 4C is a plan view showing thedamper housing and the damper base, and FIG. 4D is an enlarged viewshowing a part A2 in FIG. 4C, and FIG. 4E is a cross section view takenalong A3 in FIG. 4D.

FIGS. 5A to 5C are drawing illustrating a welding method for welding atwelding spots on a plain part, in which FIG. 5A showing an initial stageof current application, FIG. 5B is a drawing showing an expanded statusof division currents, and FIG. 5C shows a decreasing status of thedivision currents.

MODES FOR CARRYING OUT INVENTION

Embodiments of the present invention are described with reference toFIGS. 1 to 5C in which the damper housing structure body according tothe present invention is applied to a vehicle front structure, isexemplified. In explanation, the same element is designated with thesame reference, and a duplicated explanation is omitted. When adirection is explained, the explanation is made on the basis offront-rear, left-right, and up-down viewed by the driver of the vehicle.In addition, a vehicle width direction is equal in meaning to aleft-right direction.

FIG. 1 is a perspective view of a vehicle front structure of a vehicleincluding a damper housing structure body according to the embodiment ofthe present invention when downwardly viewed from a front diagonallyright. As shown in FIG. 1, a vehicle V is an automobile includes a powerunit mounting chamber P for housing a power unit such as an engine, avehicle carbine R for providing a space for crews, and wheel houses WHfor housing front wheels W. A vehicle front structure 1 according to theembodiment is a structure around a damper housing structure body 1including damper housings 2 and a damper base 3, provided on both leftand right sides of the power unit mounting chamber P.

The damper housing structure body 1 mainly includes a pair of left andright damper housings 2, the damper bases 3 provided at upper parts ofthe damper housings 2, a dash board 4 for partition between the powerunit mounting chamber P and the vehicle cabin R, a pair of upper members5 extending in a vehicle front-rear direction on the left and rightsides of the power unit mounting chamber P, and a stiffener 6 bridgingbetween the left and right damper housings 2. Further, the vehicle Vincludes a pair of left and right front side frames 7, a pair of leftand right front pillars 8, a front bulkhead 9, a pair of left and rightside sills 10, and a pair of fenders 11 (see FIG. 2), etc.

The upper member 5 is a frame member having a hollow-cross-sectionstructure, extending in the vehicle front-rear direction. The uppermember 5 is curved such that the nearer to the front of the vehicle thepart thereof is located, the more downwardly the part positions. A frontend of the upper member 5 is divided into two divisions in a verticaldirection which are connected to the front bulkhead 9. A rear end of theupper member 5 is connected to the front pillar 8. Further, on an outerside of the vehicle V, the fender 11 is provided being connected to thevehicle V each other using bolts (not shown).

The dash board 4 is a steel plate member for partitioning between thepower unit mounting chamber P and the vehicle cabin R. The dash board 4includes two members, that is, a dash board lower 4 a on a lower sidethereof, and a dash board upper 4 b on an upper side thereof. The dashboard lower 4 a is bridged between the left and right front pillars 8.The dash board upper 4 b is bridged between rear ends of the left andright upper members 5.

The front side frame 7 is a frame member having a hollow cross sectionstructure provided under the upper member 5 extending in the vehiclefront-rear direction. A front end of the front side frame 7 is connectedto the front bulkhead 9 and a rear end of the front side frame 7 isconnected to a lower end side of the dash board lower 4 a.

The front pillar 8 is a frame member having a hollow cross sectionalstructure that supports left and right ends of a front wind shield WSand left and right ends of the dash board lower 4 a. Lower ends of thefront pillars 8 are connected to front ends of a pair of the side sills10 disposed on left and right ends of the vehicle cabin R extending invehicle front-rear direction.

FIG. 2 is an enlarged perspective view showing a damper housingstructure body. Because the damper housings 2 and the damper bases 3have a left-right symmetrical structure, only the damper housing 2 andthe damper base 3 on the right side are described and descriptions aboutthe damper housing 2 and the damper base 3 on the left side are omitted.In FIG. 2, marks x indicate points welded by spot welding.

As shown in FIG. 2, the damper housing 2 is a steel member housing adamper D (see FIG. 3) and form side walls on the left and right side ofthe power unit mounting chamber P. The damper housing 2 includes aninner side wall (inner wall part) 21, a front side wall (front wallpart) 22, and a rear side wall 23 (see FIG. 3) and has a substantiallyU-shape in a plan view. The damper base 3 is fixed to an upper part ofthe damper housing 2 by welding. The inner wall 21 is, at a lower end 21a thereof, connected to the front side frame 7. On outside end parts ofthe front side wall 22 and the rear side wall 23, flanges are formed(only a flange 22 a of the front side wall 22 is shown) and connected toa vehicle inside surface 5 a of the upper member 5. Lower ends of thefront side wall 22 and the rear side wall 23 are formed in asubstantially arc in which the nearer to the inner wall 21 a partthereof is, the lower the part of the arc is positioned.

A wheel house front 25 is formed integrally with a lower end part 22 bof the front side wall 22. The wheel house front 25 curves in asubstantially arc shape of which an end on a vehicle outer side isconnected to the upper member 5, and an end on a vehicle inner side isconnected to the front side frame 7. Further, at a lower end 23 b of therear side wall 23 a damper housing extension 26 is formed integrally.The damper housing extension 26 curves in a substantially arc shape inwhich an end on the vehicle outer side is connected to the damper base3, and an end on the vehicle inner side is connected to the front sideframe 7. Further, a rear end of the damper housing extension 26 isconnected to the dash board lower 4 a. The wheel house front 25 and thedamper housing extension 26 form an upper surface of a wheel house WH.

In the present invention, the damper housing 2 includes a planar part 24at a corner part between the inner wall 21 and the front side wall 22.The planar part 24 is a seat face receiving a large load during travelof the vehicle V that is formed slantwise relative to the inner wall 21and the front side wall 22.

FIG. 3 is an exploded perspective view showing a damper housing and adamper base. As shown in FIG. 3, the damper base 3 is fixed to an upperpart of the damper housing 2 which forms a top part of the damperhousing 2, and a steel member having disk shape. The damper base 3 isformed independently from the damper housing 2 and formed to have athickness larger than that of the damper housing 2. The damper base 3includes a damper base upper wall 31 to which the damper D is installed,a damper base side wall 32 fixed to the damper housing 2.

Because the damper base 3 and the damper housing 2 are formedseparately, only a thickness of the damper base 3 receiving a large loadsuch as the load during travel is increased to prevent a thickness ofthe damper housing 2 from increasing, so that an increase in weight canbe suppressed.

At a middle of the damper base upper wall 31, an opening 31 a is formedto allow a protrusion Da in a circular hollow cylindrical shape providedon a top of the damper D to penetrate therethrough. The damper baseupper wall 31 includes three damper fixing parts 31 b around the opening31 a.

As shown in FIG. 3, the damper fixing part 31 b is a through hole forallowing bolts Db provided on a top of the damper D to penetratetherethrough. The three damper fixing parts 31 b are arranged such thatimaginary lines connecting the damper fixing parts 31 b form anequilateral triangle.

The damper base side wall 32 is a part connected to an upper edge of theinner wall 21 by spot welding and includes an inner side wall (innerwall) 32 a, a front side wall (front wall) 32 b, and a rear side wall 32c, a planar part 32 d formed at a corner part between the inner sidewall 32 a and the front side wall 32 b and has a shape overlapped withan vehicle outer side surface of the upper end of the inner wall 21.

FIGS. 4A to 4C are drawings illustrating bonding between the damperhousing and the damper base in which FIG. 4A is a perspective viewshowing the damper housing and the damper base, FIG. 4B is an enlargedview showing a part A1 in FIG. 4A, FIG. 4C is a plan view showing thedamper housing and the damper base, and FIG. 4D is an enlarged viewshowing a part A2 in FIG. 4C, and FIG. 4E is a cross section view takenalong line A3 in FIG. 4D.

As shown in FIGS. 4C to 4E, the upper edge of the damper housing 2 andthe damper base side wall 32 are connected by spot welding in anoverlapped status each other. As shown in FIG. 4A, there are a pluralityof joint points (X mark) by spot-welding at the inner wall 21, the frontside wall 22, and the rear side wall 23, and in the planar part 24,there are a plurality of the joint points (in this embodiment, there aretwo spots).

As shown in FIG. 4B, joint points, i.e., welding spots 51, 52 formed bythe spot welding at the planar part 24 are arranged in a front-reardirection of the vehicle V. The welding spot 51 previously weld includesa welding center (spot hitting point) 51 a and a welding part (nugget)51 b having a circular shape with a diameter R₁ viewed from the weldinggun 61 (see FIG. 5) which is actually joined by welding on the center ofthe welding center 51 a. Around the welding spot 51, there is a weldingmargin 51 c having a disk plate shape with an outer diameter R₂(R₂>R₁)around the welding center 51 a as a center. In other words, there is thewelding margin 51 c having the disk plate shape having the outerdiameter R₂ and the inner diameter R₁ viewed from the welding gun 61.The welding spot 52 joined later includes a welding center (spot hittingpoint) 52 a and a welding part (nugget) 52 b having a circular shapewith a diameter R₁ viewed from the welding gun 61 which is actuallyjoined by welding on the center of the welding center 52 a. Around thewelding spot 52, there is a welding margin 52 c having the outerdiameter R₂(R₂>R₁) around the welding center 52 a as a center. In otherwords, there is the welding margin 52 c having a disk plate shape havingthe outer diameter R₂ and the inner diameter R₁ viewed from the weldinggun 61. An outer diameter R₁ of the welding parts (nuggets) 51 b, 52 bvaries such that the thicker the thickness is, the larger the outerdiameter R₁ is. As defined in JIS, when a plate thickness is assumed ast_(A), the outer diameter R₁ is generally 4√t^(A). Further, the outerdiameter R₂ of the welding margins 51 c, 52 c are generally able to beset to twice the outer diameter (diameter of an electrical diameter) ofthe welding gun 61.

In the embodiment, the adjoining the welding spots 51, 52 are arrangedsuch that the welding margin 51 c is overlapped with the welding margin52 c. In other words, an interval d between the welding centers thewelding centers 51 a, 52 a of the welding spots 51, 52 adjoining eachother is shorter than the outer diameter R₂ of the welding margins 51 c,52 c, i.e., the welding margin outer diameter R₂, and the welding spots51, 52 adjoining each other are arranged so as to satisfy the followingequation.R ₁ <d<R ₂

More specifically, the interval d between the welding centers 51 a, 52 aadjoining each other is set so that the welding parts (nugget) 51 b, 52b are not overlapped and the welding margins 51 c, 52 c are overlappedeach other.

Further, it is desirable that a width w of the planar part 24 (equal toa width of the planar part 32 d) is substantially the same as outerdiameter of the welding margins 51 c, 52 c of a plurality of the weldingspots 51, 52, i.e., a sum of the welding margin outer diameters R₂.W≈2R ₂

Further, as long as a bonding strength by welding is secured, it isallowed that the width w of the planar part 24 is larger than the sum ofthe outer diameters of the welding margins 51 c, 52 c of a plurality ofthe welding spots 51, 52.

In the embodiment, the two welding spots 51, 52 are arranged so as topinch a ridgeline L1 (see FIG. 4D) when the corner part between theinner wall 21 and the front side wall 22 shows a curved shape. In otherwords, the two welding spots 51, 52 are arranged to pinch a center in awidth direction of the planar part 24.

Next, a method of producing the damper housing structure body accordingto the embodiment of the present invention, particularly, a method ofwelding the welding spots 51, 52 at the planar part 24 is mainlydescribed with reference to FIGS. 5A to 5C. FIGS. 5A to 5C are drawingsillustrating a welding method at a welding spot at the planar part inwhich FIG. 5A shows a status of a current conduction initial stage, FIG.5B shows a status in which division currents are expanded, and FIG. 5Cshows a status in which the division current decreased.

A joule heat Q upon welding is expressed by the following equation.Q=0.24·I ² ·r·twhere I: Current, r: resistance, and t: current application period.

When the welding spots 51, 52 are sequentially formed, i.e., afterformation of the welding spot 51, a welding spot 52 is formed, a shuntcurrent is generated at the welding spot 51 when the welding spot 52 isformed, so that a current flowing in the welding spot 52 decreases.Accordingly, to cover the shunt current, it is necessary that thecurrent I in the Joule heat equation is increased or a currentconduction period t is extended. However, it is possible that extensionof the current conduction period t makes a diameter of the nugget(current conduction diameter) large. However, because this influences anoperation period, in the present embodiment, an appropriate diameter isprovided by adjusting a value of the current I.

First, as shown in FIG. 5A, in a status in which the welding part 51 bis formed by previously welding the welding spot 51, a pair of thewelding guns 61, 61 are arranged so as to pinch a welding center 52 a ofthe welding spot 52, and a current application is carried out for spotwelding. The current value for the spot welding at the welding spot 52can be set to a value higher than the current value for spot welding atthe welding spot 51 which has been previously welded. This is a countermeans in consideration of occurrence of the shunt current at the weldingspot 51 upon welding the welding spot 52.

More specifically, as shown in FIG. 5A, at the current conductioninitial stage, in addition to the current forming a welding part 52 bvia a resistor r₁ on the side of the damper housing 2 and a resistor r₂on a side of the damper base 3, a shunt current on a side of the nugget51 b via a resistor r₃ on the side of the damper housing 2 and aresistor r₄ on a side of the damper base 3 occur.

As shown in FIG. 5B, when heat is generated by the current conduction atthe welding part 52 b, resistances of the resistors r₁ and r₂ increase,so that a value of a current flowing through the welding part 52 bdecreases, so that a current value of the shunt current increases.

Next, as shown in FIG. 5C, when the welding part 52 b is expanded bycurrent conduction, this decreases the resistors r₁, r₂, and a value ofa current flowing through the 52 b increases, so that a current value ofthe shunt current decreases.

The current value upon bonding at the welding spot 52 depends onmaterials of the damper housing 2 and the damper base 3. However, forexample, the current value is set to a value higher than the currentvalue at the welding spot 51 by about 500 to 1500 A. When an increase inthe current value from the current value upon welding the welding spot51 is less than 500 A, the shunt current to the welding spot 51 becomeslarge, so that there may be a case where an appropriate nugget diameterat the welding spot 52 may not be secured. In addition, the increasefrom the current value upon welding the welding spot 51 exceeds 1500 A,spatter is generated to a considerable extent at the current conductioninitial stage, so that the resistors r₁, r₂ decrease, which may notsecure an appropriate value of nugget's outer diameter R₁ at the weldingspot 52.

In the damper housing structure body according to the embodiment of thepresent invention, the spot welding is carried out at the planar part 24at the corner part between the inner wall 21 and the front side wall 22of the damper housing 2 at a narrow interval. Accordingly, it becomespossible to provide the welding spots 51, 52 at a narrow space part,which was conventionally difficult, so that a strength enough to standthe travelling load in the damper housing 2 can be secured. Further, anincreased strength can reduce the plate thickness of the damper housing2, so that weight saving of the vehicle body and cost reduction can beprovided. Further, a plurality of the welding spots 51, 52 are properlydistributed, which decreases a total number of the impacts, so thatadvantageous effects in cost reduction and decrease in man-hour can beprovided. Further, a ridge line L2 between the front side wall 22 andthe planar part 24 and a ridge line L3 between the inner wall 21 and theplanar part 24 appropriately disperse the traveling load inputted intothe damper housing 2 from a downward direction to avoid loadconcentration.

In the damper housing structure body according to the embodiment of thepresent invention, a plurality of the welding spots 51, 52 are notformed instantaneously, but sequentially formed, so that when one of thewelding spots 52 is weld, currents are conducted at other welding spots51 which have been formed to provide joint at a plurality of weldingspots. Accordingly, it becomes possible to provide the welding spots 51,52 at the narrow space part, which was conventionally difficult, so thatthe strength to sand the travelling load can be secured in the damperhousing 2. Further, an increased strength can reduce a plate thickens ofthe damper housing 2, which results in weight saving and cost reductionof the vehicle body. Further, a proper allocation of the welding spots51, 52 can decrease the total number of the impacts, which provides costreduction and decrease in man-hours.

Further, in the damper housing structure body according to theembodiment of the present invention, when one of the welding spots 52 iswelded, the welding spot 52 is welded with a current having a valuehigher than currents for welding other the welding spots 51.Accordingly, the welding spots 51, 52 can be provided appropriately atthe narrow part, which was conventionally difficult to be welded, sothat the damper housing 2 is provided with the strength enough to standthe travelling load. Further, the increased strength makes it possibleto reduce the plate thickens in the damper housing 2, so that weightsaving and cost reduction are provided. Further, the total impact spotscan be reduced in the number, so that cost reduction and reduction inman-hour are provided by appropriately allocation of the welding spots51, 52.

Further, in the damper housing structure body according to theembodiment of the present invention, because the width of the planarpart 24 is substantially the same as the sum of outer diameters of thewelding margins, the damper housing 2 can have the strength to sand thetravelling load. Further, the increased strength makes it possible toreduce the plate thickness in the damper housing 2, which providesweight saving and cost reduction of the vehicle body. Further,appropriate allocation of the welding spots 51, 52 results in the totalnumber of impact spots, which provides advantageous effects in the costreduction and reduction in man-hours.

As mentioned above, the embodiment of the present invention has beendescribed. The present invention is not limited to the above-describedembodiment, but may be appropriately modified without departure of thesubject matter of the present invention. For example, the number of thewelding spots (n being a natural number of three or more) at the planarpart 24 may be three or more. When n welding spots are arranged in theplanar part 24 in a front-rear direction of the vehicle V, the width wof the planar part 24 is desirable to satisfy the following equation:w≈n·R ₂

DESCRIPTION OF REFERENCE SYMBOLS

-   1 damper housing structure body-   2 damper housing (damper housing structure body)-   3 damper base (damper housing structure body)-   21 inner side wall (inner wall)-   22 front side wall (front wall)-   24 planar part-   51, 52 welding spot-   51 c, 52 c welding margin-   D damper

The invention claimed is:
 1. A damper housing structure body comprising:a damper housing configured to house a damper of a suspension device ofa vehicle; and a damper base, disposed at a top of the damper housing,fixed to the damper, wherein an upper edge of the damper housing and thedamper base are bonded by spot welding, wherein the damper housinghaving a U-shape in a plan view thereof with an opening toward a vehicleouter side and including a planar part at a corner part between a frontwall and an inner wall, wherein the planar part includes a plurality ofwelding spots arranged in a vehicle front-rear direction, wherein thewelding spots adjoining each other have welding margins which areoverlapped with each other, and wherein one of the welding spots isformed by being welded while a current is applied to another one of thewelding spots that has been already welded.
 2. The damper housingstructure body defined by claim 1, wherein a width of the planar part issubstantially the same as a sum of outer diameters of a plurality of thewelding spots.
 3. The damper housing structure body defined by claim 1,wherein one of the welding spots if formed by welding using a currentvalue higher than another current value used for welding another one ofthe welding spots that has been already welded.
 4. A damper housingstructure body comprising: a damper housing configured to house a damperof a suspension device of a vehicle; and a damper base, disposed at atop of the damper housing, fixed to the damper, wherein an upper edge ofthe damper housing and the damper base are welded by spot welding,wherein the damper housing having a U-shape in a plan view thereof withan opening toward a vehicle outer side and including a planar part at acorner part between a front wall and an inner wall, wherein the planarpart includes a plurality of welding spots arranged in a vehiclefront-rear direction, wherein the welding spots adjoining each otherhave welding margins, and an interval between two of the welding spotsadjoining each other is shorter than an outer diameter of the weldingmargins, and wherein one of the welding spots is formed by being weldedwhile a current is applied to another one of the welding spots that hasbeen already welded.
 5. The a-damper housing structure body defined byclaim 4, wherein a width of the planar part is substantially the same asa sum of outer diameters of a plurality of the welding spots.
 6. Thedamper housing structure body defined by claim 4, wherein one of thewelding spots if formed by welding using a current value higher thananother current value used for welding another one of the welding spotsthat has been already welded.
 7. A damper housing structure bodycomprising: a damper housing configured to house a damper of asuspension device of a vehicle; and a damper base, disposed at a top ofthe damper housing, fixed to the damper, wherein an upper edge of thedamper housing and the damper base are bonded by spot welding, whereinthe damper housing having a U-shape in a plan view thereof with anopening toward a vehicle outer side and including a planar part at acorner part between a front wall and an inner wall, wherein the planarpart includes a plurality of welding spots arranged in a vehiclefront-rear direction, wherein the welding spots adjoining each otherhave welding margins which are overlapped with each other, and whereinone of the welding spots if formed by welding using a current valuehigher than another current value used for welding another one of thewelding spots that has been already welded.
 8. The damper housingstructure body defined by claim 7, wherein a width of the planar part issubstantially the same as a sum of outer diameters of a plurality of thewelding spots.
 9. A damper housing structure body comprising: a damperhousing configured to house a damper of a suspension device of avehicle; and a damper base, disposed at a top of the damper housing,fixed to the damper, wherein an upper edge of the damper housing and thedamper base are welded by spot welding, wherein the damper housinghaving a U-shape in a plan view thereof with an opening toward a vehicleouter side and including a planar part at a corner part between a frontwall and an inner wall, wherein the planar part includes a plurality ofwelding spots arranged in a vehicle front-rear direction, wherein aninterval between two of the welding spots adjoining each other isshorter than an outer diameter of the welding margins, and wherein oneof the welding spots if formed by welding using a current value higherthan another current value used for welding another one of the weldingspots that has been already welded.
 10. The damper housing structurebody defined by claim 9, wherein a width of the planar part issubstantially the same as a sum of outer diameters of a plurality of thewelding spots.